Black-tailed Deer

Frequent preserve visitors often encounter deer, although they will likely run away if you are too close. The range of black-tailed deer extends from southern California to Canada, although individuals’ home territories extend only a mile or so. Deer prefer habitat that includes tree cover — for shelter and safety — and open grasslands or chaparral for tasty shrubs with new leaves, although they will eat a wide variety of plants, including oaks and berries. They are a key prey species for mountain lions. After rising for decades, California’s deer populations have been declining due to habitat loss.

Interesting Facts

Did you know

The antlers of males (called bucks) fall off each year

Fun math

Black-tailed deer often have twins

Reaction to humans

Skittish, deer will flee if you approach too close

Other animals in our preserves

Mountain lions — also called pumas or cougars — are the top predator (other than humans) in the Santa Clara Valley. They live alone and are most active at night. Mountain lions are big: males can be more than 8 feet long and weigh over 120 pounds. Pumas can climb trees and may be found up to 50 feet up a tree. They primarily eat deer but also eat raccoons, birds, foxes, and mice. Cougars need large amounts of connected open spaces for hunting, water sources, and den sites. Mountain lion attacks on humans are exceptionally rare. If you encounter a lion, look big and stay with others. If attacked, fight back and be loud. Do not try to run away.

Tule elk are the smallest elk in North America and are only found in California. They are distinguished by their white rump. Each year, males grow a new rack of antlers, which become progressively larger as they age. The breeding season, called the rut, occurs primarily in September, when males compete to mate and claim possession of a group of females. Tule elk were hunted throughout the 1800s and their population was also effected by habitat loss. Now, 5,100 tule elk are thought to live in California, including some who can be found Coyote Ridge Open Space Preserve.

Hard to spot, badgers are nocturnal, solitary, and spend much of their time underground. You’ll know if you spy one though — they are brownish, with short legs, an angular face, and a distinctive white stripe that stretches from the nose to the top of the head. General carnivores, badgers will eat rats, squirrels, mice, insects or birds. Skillful diggers, badgers burrow to catch prey but also to sleep, although they may switch burrows daily. California’s badgers are American badgers, which live throughout the western United States. Interestingly, badgers are also found in Europe (called European badgers), but they are social, rather than solitary.

Burrowing owls are found throughout the western United States in open grasslands, although their population has declined due to the loss of open spaces. Visitors to Sierra Vista Open Space Preserve may be able spot these 8-inch tall birds, which have brown-tan splotched feathers and bright yellow eyes. The owls eat a variety of insects and small reptiles including grasshoppers, beetles, crickets, and lizards. Females spend one month incubating about eight eggs each year. During that time, their male partners bring them food.

Acorn woodpeckers are primarily black, with patches of white on their faces and wings, with a bit of red on their heads. They are found in oak woodlands along the Pacific coast, from Washington to Colombia in South America. True to their name, acorn woodpeckers eat acorns, which they stash in holes they drill in trees. Some of these holes contain thousands of acorns! They also munch on flying insects. Woodpeckers live in communal groups of about a dozen individuals, who contribute by gathering food and raising young. The breeding relationships are complicated, with several males and females mating in each group.

Yellow-billed magpies are primarily black birds, with long tail feathers, white sides, blue iridescent wing and tail feathers, and their namesake yellow-bill. Although species of magpies are worldwide, the yellow-billed magpie is found only in a small sliver of California’s central valley and coast range, where it lives in oak woodlands. The species is thought to be at risk from climate change due to its restricted range and specific habitat needs, which include mature trees and open grassland. They primarily eat insects such as grasshoppers. Yellow-billed magpies build domed nests out of sticks and mud in a tall tree — about 50 feet off the ground.

Red-legged frogs are 2 to 5 inches long, brown or olive-colored, with red on parts of the belly and legs. These frogs are classified as “threatened” under the federal Endangered Species Act due primarily to the loss of wetland habitat, although they also face threats from non-native bullfrogs. They are found in Sierra Vista and Rancho Cañada del Oro open space preserves, but are active primarily at night so visitors are unlikely to spot them. During their winter breeding season, females can lay as many as 3,000 eggs in shallow water. After hatching, the tadpoles mature — or metamorphose — into frogs about five months later.

The yellow-eyed Ensatina is an orange-brown salamander that is about 5 inches long. These salamanders have no lungs — instead they breathe through their skin and mouth. That’s why you are mostly likely to spot them in moist spots under fallen branches or in tree cavities, although they may be on a trail following a rain. Providing homes for creatures like Ensatina is one reason it is important to leave downed trees undisturbed. They eat worms, beetles, spiders, and a variety of other invertebrates. Females lay around 12 eggs on land in the late spring, which they guard until the babies emerge in the fall.

Western fence lizards are about 3 inches long with bits of blue on their bellies. Males are often observed doing a push-up like display to defend their territory and to attract females. Lizards are a staple food of snakes and birds of prey like hawks. Western fence lizards, a subspecies of the coast range fence lizard, have an interesting relationship with Lyme disease: Their blood contains a protein that kills the bacteria that causes Lyme disease. However, the lizards are a key host for ticks that carry Lyme disease, so there are more ticks in western fence lizard habitat.

The western pond turtle lives in wetlands, ponds, and streams and can often be spied in the spring, summer, and fall sunbathing on a rock or log. It may spend the winter buried in a shallow dugout in the woods. They are approximately 5-6 inches long and olive or brown colored. The western pond turtle is found from Oregon to Baja California primarily west of the Sierra Nevada, although they have lost habitat due to development and the arrival of non-native bullfrogs and turtles such as the red-eared slider. They eat worms, aquatic plants, small fish, and insects.

Rattlesnakes are the only type of venomous snake found in the Santa Clara Valley. You are most likely to spot one on a hot day when they may be sunbathing on a trail or exposed rock. They have triangular heads and chunky olive or tan striped bodies. Their tails have a set of rattles at the end, made of keratin, the same material found in your fingernails. Snakes vibrate the rattles when alarmed and may also hiss. Be warned: Rattlesnake venom is highly toxic. Rattlesnakes eat a variety of small mammals, lizards, and birds. They hibernate during the winter.

The California brown tarantula is brownish-black and can grow to 5 inches long. Although they may look intimidating, a tarantula’s venom can subdue only beetles, grasshoppers, or small spiders — they don’t harm humans. The spiders live underground and are primarily active at night. In the fall, males emerge and wander in search of females. You are most likely to spot them in Rancho Cañada del Oro or Sierra Vista open space preserves. When a male finds a female’s silk-lined burrow, he knocks to announce his arrival. Males die within weeks of mating, but females can live to be 25 or 30 years old.